There has been wide spread use of keypads and other input devices to provide secure access to buildings or other objects, e.g., safes, automobiles, jail cells, etc. In conjunction with this trend, electric unlocking devices such as, for example, electrified door locks and electric door strikes are routinely used to control entry or access by means of a remote switch or other trigger. For example, it is frequently desirable in a security application to energize an actuator, such as for example a solenoid, used in engaging/disengaging an electric door strike. There may be varying modes of operation for an electric door strike, commonly referred to as “Fail Secure” and “Fail Safe”.
In the fail secure mode, a loss of power leaves the door strike in the locked condition. The solenoid that drives the strike to unlock the door may be powered only briefly to unlock the door, and because of the low duty cycle, the average power demand is low. In certain applications (i.e., employer entrance doors) the fail secure strike may be powered for eight or more hours while the door strike is held in an unlocked mode.
In the fail safe mode, the door strike is unlocked by a loss of power. Fail safe strikes are powered continuously except while the door is unlocked. This requires a high duty cycle with relatively high average power demands and heat dissipation. Reducing the heat dissipation in the circuit for such a unit is very desirous for longevity, user safety, etc.
Installers of electric unlocking devices such as electric door strikes are constantly confronted by the lack of standardization in the industry relative to supply voltage for strike operation. Some strikes are designed to operate at 12 or 24, or up to 40 volts DC; others are designed for 12, 16 or 24 VAC. As such, supply voltages ranging from 12 to 40 Volts DC or 12 to 28 Volts AC may be present at a particular location and the installer would need to match the device to the available voltage. As a result, the installer needs to stock a supply of various versions of door strikes and sometimes make complicated adjustments at a consumer site. This creates the opportunity for errors in strike installation or configuration.
It is desirable to provide a system that simplifies installation while accommodating the variations in actuating coil requirements. It is also desirable to determine if an error has been made in the connection of an electric unlocking device, or to receive an indication of other problems with the control circuit. This status information must be readily observable without the need for other equipment or diagnostic tools.
What is needed is a robust and efficient solution that can be universally implemented without the drawbacks described above. A solution that provides simplified and universal connectivity to existing unlocking devices, or new installations of such devices, feedback to the installer, and troubleshooting or diagnostic status while avoiding the short comings of current systems, would be advantageous.
The present invention fulfills these as well as other needs.